^^^ rROCEEDINGS OF THE ACADEMY OF [Murcll, 



the chromatin nucleoli. The nine remaining elements are likewise 

 all dumbbell-shaped, but on pole view of the spindle (fig. 14) 

 each of them appears elongate, sometimes showing a split in the 

 long axis. On lateral views of the spindle (figs. 15. 16) they 

 sometimes appear bipartite, sometimes quadripartite. As a study 

 of them in the preceding prophases demonstrates, each becomes 

 placed in the equatorial plane of the spindle so that the transverse 

 split (the line of junction of the two component univalent clu"o- 

 raosomes) lies in the equator of the spindle, and the longitudinal 

 split of each univalent chromosome lies perpendicular to this 

 plane. Thus the nine larger chromatin elements of fig. 14 appear 

 elongate on pole view of the spindle, because each of these bivalent 

 chromosomes is composed of two univalent chromosomes with 

 their long axes parallel to one another and to the equatorial plane 

 of the spindle. Hence on pole view of this spindle we see a plate 

 of (univalent) chromosomes, each seen longitudinally ; Avhereas 

 such a view in the other Hemiptera studied by me shows the 

 chromosomes seen from their ends, since in other Hemiptera it is 

 the general rule that two univalent chromosomes are joined end to 

 end, and not (as in Nahis) side to side. 



All ten elements divide transversely in this mitosis, so that whole 

 univalent elements become separated from one another. A pole 

 view of one of the plates of daughter chromosomes resulting from 

 this division (fig. 17) shows one smallest element (/>.), the half 

 of the corresponding element of figs. 14 and 16, and nine larger 

 elements, the halves of those of fig. 14. In fig. 17 each of the 

 nine larger univalent elements shows a well-marked longitudinal 

 split, which had been uauilly hiddvn in the preceding monaster 

 stage (fig. 14) ; it is a general rule in the Hemiptera that the longi- 

 tudinal split becomes temporarily hidden in the monaster stage of 

 the first maturation mitosis. 



One point needs to be emphasized: there are in the prophases 

 four chromatin nucleoli and six chromosomes, and in the monaster 

 stage of the first mitosis again ten elements, that is, ubviously 

 the same as those in the prophases. But the four chromatin 

 nucleoli of the prophases (figs. 12, 13) are smaller than any of 

 the chromatin elements of the monaster stage (fig. 14), except 

 the small element in the latter marked p. Accordingly three at 

 least of the chromatin nucleoli must have increased in volume 



